bug-of-the-month club

bug-of-the-month club /n./ [from "book-of-the-month
club", a time-honored mail-order-marketing technique in the U.S.]
A mythical club which users of `sendmail(1)' (the UNIX mail
daemon) belong to; this was coined on the Usenet newsgroup
comp.security.unix at a time when sendmail security holes, which
allowed outside crackers access to the system, were being
uncovered at an alarming rate, forcing sysadmins to update very
often. Also, more completely, `fatal security bug-of-the-month
club'.